Upgrade Slf4j 1.7.5, close #307

Author: Stephane Landelle

api/pom.xml

@@ -34,7 +34,7 @@
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
-            <version>1.6.2</version>
+            <version>1.7.5</version>
         </dependency>
     </dependencies>
 

pom.xml

@@ -500,7 +500,7 @@
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
-            <version>0.9.26</version>
+            <version>1.0.13</version>
             <scope>test</scope>
         </dependency>
         <dependency>